1. Field of the Invention
The invention relates generally to agents and methods for preventing a viral or microbial infection and, more specifically, to compositions containing a xcex2-cyclodextrin and methods of using such compositions to reduce the risk of transmission of a sexually transmitted disease.
2. Background Information
Sexually transmitted diseases (STDs) are among the most common types of infections. Three bacterial STDsxe2x80x94gonorrhea, chlamydial infections, and syphilisxe2x80x94are particularly common, and account for a great deal of morbidity, including infertility, ectopic pregnancy, and loss of productivity (see Harrison""s xe2x80x9cPrinciples of Internal Medicinexe2x80x9d 13th edition (ed. Isselbacher et al.; McGraw-Hill, Inc. 1994), chapter 88). Among the viral STDs, human papilloma virus and hepatitis B virus are among the most common, and are associated with cervical carcinoma and hepatocellular carcinoma, respectively.
In the past couple of decades, acquired immunodeficiency disease (AIDS) associated with sexual transmission of human immunodeficiency virus (HIV) has emerged as a global health threat. In industrialized countries, education as to the use of condoms and the practice of xe2x80x9csafe sexxe2x80x9d reduced the levels of new HIV infection and of AIDS deaths following a peak in the mid-1990""s. However, the decreased number of AIDS deaths and the availability of medications that appear to increase the life spans of AIDS patients may have created a false sense of security, and it now appears that this trend may reverse. In many non-industrialized countries, AIDS is an epidemic, and it is not inconceivable that millions may die from this disease in the next few years.
HIV can be transmitted in a number of ways, including through contaminated blood products, and from mother to offspring during gestation, child birth or breast feeding. However, newly acquired HIV infections are largely the result of sexual contact, particularly heterosexual contact. A number of factors appear to determine whether HIV is transmitted sexually, including the type of sex act, susceptibility of the exposed partner, infectivity of the infected partner, and the biological properties of the particular HIV subtype.
Prevention of the spread of HIV infection requires interventions of both the infected and uninfected populations. In particular, since only a small percentage of HIV-infected individuals are aware of their carrier status, a significant prevention effort must be made by the susceptible population. Mechanical barriers such as condoms can be effective in preventing sexual transmission of HIV. However, this method is not always accepted by male partners, and can be impractical for use by women. Topical microbicides currently available have proven inadequate, and the widely used surfactant microbicide, nonoxynol-9, which is used as a spermicide, may actually increase HIV infection by inducing genital ulcerations. Thus, in the absence of an effective vaccine, other biomedical methods must be identified, particularly those that can be practiced by the susceptible population.
Semen from HIV infected men and cervical mucus from HIV infected women contain free virus as well as HIV-infected cells and, sexual transmission of HIV may occur due to both forms of the virus. Thus, a need exists for a therapeutic agent that reduces or eliminates transmission of free HIV as well as cell-associate virus infection, thereby reducing the risk of transmission of HIV and other sexually transmitted pathogens. The present invention satisfies this need and provides additional advantages.
The present invention relates to methods of reducing the risk of transmission of a sexually transmitted pathogen, including cell-associated and cell-free sexually transmitted pathogens. In one embodiment, a method of the invention is performed by contacting the pathogen or cells susceptible to infection by the pathogen with a xcex2-cyclodextrin (xcex2CD). The pathogen can be any pathogen involved in the etiology of a sexually transmitted disease, particularly a pathogen that infects a susceptible cell through contact with lipid rafts in the membrane of the cell. As such, the pathogen can be an enveloped virus, for example, an immunodeficiency virus such as human immunodeficiency virus (HIV), a T lymphotrophic virus such as human T lymphotrophic virus (HTLV), a herpesvirus such as a herpes simplex virus (HSV), a measles virus, or an influenza virus. The pathogen also can be a microbial pathogen, for example, a bacterium, a yeast such as a Candida spp., a mycoplasma, a protozoan such as a Trichomona spp., or a Chlamydia spp. The xcex2CD can be any xcex2CD derivative, for example, 2-hydroxypropyl-xcex2-cyclodextrin.
In another embodiment, a method of the invention provides a means to reduce the risk of transmission of a sexually transmitted pathogen to or from a subject, which can be any subject susceptible to a sexually transmitted disease, for example, a vertebrate, particularly a mammal, including a human. Such a method can be performed, for example, by contacting the pathogen or cells susceptible to infection by the pathogen in the subject with a pharmaceutical composition comprising a xcex2-cyclodextrin (xcex2CD), thereby reducing the risk of the subject becoming infected with the sexually transmitted the pathogen. Such a method also can be performed, for example, by contacting the pathogen or cells susceptible to infection by the pathogen in a subject having a sexually transmitted disease with a pharmaceutical composition comprising a xcex2CD, thereby reducing the risk of transmission of the sexually transmitted disease by the subject.
The cells susceptible to infection by the pathogen can be any cells depending, in part, on the pathogen, including epithelial cells, particularly vaginal epithelial cells or rectal epithelial cells. Furthermore, the cells susceptible to infection, as well as the pathogen in a cell-free form, can be present in a secretion produced by the subject, for example, in semen or in a vaginal secretion. The pharmaceutical composition can be formulated in a solution, a gel, a foam, an ointment, a cream, a paste, a spray, or the like; or can be formulated as a component of a suppository, a film, a sponge, a condom, a bioadhesive polymer, a diaphragm, or the like; and can contain, in addition to the xcex2CD, one or more agents useful to a sexually active subject, for example, a contraceptive, an antimicrobial or antiviral agent, a lubricant, or a combination thereof.
The present invention also relates to a pharmaceutical composition, which includes 1) xcex2CD, which is in an amount that blocks passage of the pathogen through lipid rafts in the membrane of a cell susceptible to the pathogen, and 2) a contraceptive, an antimicrobial or antiviral agent, a lubricant, or a combination thereof. A contraceptive useful in a pharmaceutical composition of the invention can be any contraceptive, for example, a spermicide. Similarly, an antimicrobial or antiviral agent for treating a sexually transmitted disease can be any agent that generally is used to treat or prevent infection by a sexually transmitted pathogen, or an opportunistic pathogen associated with a sexually transmitted disease, including, for example, an antibiotic.
The present invention further relates to a composition, comprising a solid substrate that contains an amount of xcex2CD useful for reducing the risk of transmission of a sexually transmitted pathogen. The solid substrate can be a barrier, which is composed of a relatively impermeable substrate, for example, a condom, diaphragm, vaginal film or glove, which contains the xcex2CD at least on its surface; or can be composed of an absorptive material, for example, a sponge or a tampon, which contains the xcex2-cyclodextrin incorporated therein.